This invention relates to aqueous solutions of amino group-containing silanol compounds, glass substrates and glass fibers which are surface-treated with the solutions, and processes for the preparation of aqueous solutions of amino-containing silanol compounds.
Hydrolyzable silanes which have been extensively used as silane coupling agents and surface treating agents for various substrates are utilized after a hydrolyzable group in the silanes has been hydrolyzed.
Japanese Patent No. 2508554 discloses, as an example of such hydrolyzable silanes, aqueous solutions of amino group-containing silanol compounds prepared by hydrolyzing aminoalkoxysilanes and removing by-producing alcohols. The amino group-containing silanol compounds, which have undergone the hydrolysis and removal of the by-producing alcohols, are materials wherein a volatile organic compound such as an alcohol is relatively difficult to generate when used in the surface treatment.
However, the aqueous solutions of amino group-containing silanol compounds disclosed in Japanese Patent No. 2508554 might lack storage stability, depending on storage conditions. Moreover, when the aqueous solutions of amino group-containing silanol compounds were allowed to stand in contact with air, ethyl alcohol exceeding 1000 ppm (0.1 MPa, 25xc2x0 C.) which is an allowable concentration advised by the American Conference of Governmental Industrial Hygienists (ACGIH) might be emitted into air, depending on the conditions under which they are allowed to stand.
We have made intensive studies in view of the problems in the above-mentioned prior art, and found that an aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound is excellent in storage stability and can control the emission of a volatile organic compound into air below the allowable concentration, said silanol compound being prepared by reacting 1 mole of an aminoalkyl silane represented by the formula (1) with 1.5 to 10 moles of water and distilling off a volatile organic compound by-producing during the reaction. The present invention has been accomplished on the basis of this finding.
H2N(CH2)nSi(R)3xe2x80x83xe2x80x83(1)
wherein R is a hydrolyzable group and n is an integer of 1-6.
The present invention is composed of the following items (1) to (14).
(1) An aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound, prepared by reacting 1 mole of an aminoalkylsilane represented by the formula (1) with 1.5 to 10 moles of water and distilling off a volatile organic compound by-producing during the reaction.
H2N(CH2)nSi (R)3xe2x80x83xe2x80x83(1)
xe2x80x83wherein R is a hydrolyzable group and n is an integer of 1 to 6.
(2) The aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound according to the item 1, wherein the content of silicon is in the range of 7.5 to 17% by weight.
(3) The aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound according to the item 1, wherein it is prepared using an aminoalkylsilane of the formula (1) wherein R is an alkylalkoxy group of 1 to 4 carbon atoms.
(4) The aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound according to the item 1, wherein it is prepared by carrying out the reaction of an aminoalkylsilane with water and the removal of a by-producing volatile organic compound by distillation in the range of 0 to 150xc2x0 C.
(5) The aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound according to the item 1, wherein it is prepared by distilling off a by-producing volatile organic compound under reduced pressure in the range of 1 Pa to 0.1 MPa.
(6) The aqueous solution of an amino group-containing silanol compound containing less than 4% by weight of a by-producing volatile organic compound according to the item 1, wherein it is prepared by adding to a reaction solution water of the same weight as the volatile organic compound distilled off from the reaction solution, in the distillation of the by-producing volatile organic compound.
(7) A surface treating agent comprising the aqueous solution of an amino group-containing silanol compound as defined in any one of the preceding items 1 to 6.
(8) A glass substrate which is surface treated with the aqueous solution of an amino group-containing silanol compound as defined in any one of the preceding items 1 to 6.
(9) A glass fiber which is surface treated with the aqueous solution of an amino group-containing silanol compound as defined in any one of the preceding items 1 to 6.
(10) A process for the preparation of an aqueous solution of an amino group-containing silanol compound, which comprises reacting 1 mole of an aminoalkylsilane of the formula (1) as set forth in the item 1 with 1.5 to 10 moles of water and distilling off a volatile organic compound by-producing during the reaction until its content is less than 4% by weight.
(11) The process for the preparation of an aqueous solution of an amino group-containing silanol compound according to the item 10, wherein the aminoalkylsilane of the formula (1) as defined in the item 1 wherein R is an alkylalkoxy group of 1 to 4 carbon atoms is used.
(12) The process for the preparation of an aqueous solution of an amino group-containing silanol compound according to the item 10, wherein the reaction of an aminoalkylsilane with water and the removal of a by-producing volatile organic compound by distillation are carried out in the range of 0 to 150xc2x0 C.
(13) The process for the preparation of an aqueous solution of an amino group-containing silanol compound according to the item 10, wherein the by-producing volatile organic compound is distilled off under reduced pressure in the range of 1 Pa to 0.1 MPa.
(14) The process for the preparation of an aqueous solution of an amino group-containing silanol compound according to the item 10, wherein water of the same weight as the volatile organic compound removed by distillation from a reaction solution is added to the reaction solution, in the distillation of the by-producing volatile organic compound.